1. Technical Field
The present disclosure relates generally to the field of telecommunications and data networks. More particularly, in one exemplary aspect, the present disclosure is directed to the intelligent management of subordinate nodes in a wireless network.
2. Description of Related Technology
3GPP Long Term Evolution (LTE) is a wireless data communications technology that increases the capacity and speed of cellular data networks by using advanced wireless communications modulation techniques. While the high data rates seen in LTE are relatively easy to maintain when close to an evolved Node B (eNB), low signal strength as a result of increased distances from an eNB, as well as interference from neighboring eNBs, can detrimentally affect LTE communication data rates. Network providers have begun addressing these issues through the deployment of heterogeneous networks, in which smaller communications subordinate nodes are deployed throughout a larger node (i.e., a macro-cell). FIG. 1 shows a heterogeneous network 100 that consists of macro-cells consisting of respective eNBs 102 that are further divided into smaller sub-cells consisting of subordinate transmission/reception nodes 104 (e.g., picocells, femtocells, or distributed antenna systems using remote radio heads). These sub-cells may or may not share the same cell identity with the macro-cell. From the perspective of the network, only the macro-cell (or alternatively a cell with a unique physical layer identifier) can be recognized and interfaced with. Accordingly, if the subordinate nodes (e.g., remote radio heads) share the same cell identifier with the macro-cell, then the subordinate nodes are transparent to the network (i.e., the network cannot individually interface with the subordinate nodes). As illustrated in the system 200 of FIG. 2, the in-bound information to those subordinate nodes 206 will be distributed through the eNB 204, and the out-bound information from those nodes 206 will be collected and sent to the network 202 by the eNB 204.
In implementations in which each subordinate node and its respective macro-cell each possess a unique physical layer identity (from the perspective of the network), the network would be required to recognize and transmit and/or receive information from each node separately. For example, within the context of LTE, the network would need separate S1-U interfaces (i.e., the network interface between the eNB and the serving gateway (GW)) and S1-MME interfaces (i.e., the network interface between the eNB and the mobility management entity (MME)) for each node and subordinate node, as well as separate X2 interfaces (i.e., the network interface between eNBs) between each of the nodes. In addition to the large amount of communication overhead required for such an implementation, the network also must coordinate the operation of eNBs with subordinate nodes, where each subordinate node may be unpredictably turned on and off.
Consequently, the sharing of the same cell identifier by neighboring nodes undesirably increases intra-cell interference, and degrades the channel estimation performance and coherent detection of data and control channels. The sharing of the same physical layer cell identity also limits the use of certain technologies, such as e.g., advanced closed-loop single user multiple input multiple output, multiple user multiple input multiple output (SU-MIMO/MU-MIMO) beamforming techniques. Furthermore, the use of the same physical layer cell identity by subordinate nodes prevents subordinate node identification and switching.
Accordingly, improved apparatus and methods are needed to improve upon the handling of subordinate nodes within a given macro-cell. Such improved apparatus and methods would ideally be transparent from the perspective of core network management and control.